3.5l Ecoboost Misfire/Catalytic Converter

[whynotzoidberg]

Hey y'all,

I've dug around the old forums for a bit and found a few similar situations, but everyone seems to have taken their vehicle to a dealer who threw a bunch of parts at it and didn't fix the problem. I don't let shops, especially dealerships, do work on my vehicles (bad experiences with my Powerstroke back in high school), so I'm hoping someone has an answer.

I took my '17 Sport, which now has 65k miles, on a small road trip last week to pick up parts from a junkyard, and right as I was pulling into my neighborhood I got a misfire, which was narrowed down to spark plugs. Replaced the plugs, but immediately after the CEL came on, and my OBD II gave me the Catalytic Converter Below Efficiency Threshold. Erased the code to see if it was related, and it was fine until this morning when it came back while I was on the freeway. Engine runs fine, no shaking, no loss in power or fuel efficiency, but the code is on. Any thoughts?

 

[fast_dave]

Just askin' @whynotzoidberg


While you were replacing your plugs, did you disconnect the battery to clear the computer of all the old parameters it learned while driving with the bad plug???

I'd start with that before throwing any more parts at it.

 

[peterk9]

What was the code designation? Was it P0420?

Google Search

Peter

 

[whynotzoidberg]

Y'know, I think I may have said I was going to, but maybe I didn't. I'll do that first. Thanks

 

[whynotzoidberg]

What was the code designation?

Peter

P0420

 

[peterk9]

P0420

I guess you were replying at the time I posted above. The link I included shows there are several things that can cause that code so it is really "cut and dry". That is likely why dealers are trying different strategies. You may end up doing the same.

Peter

 

[whynotzoidberg]

I reset the computer and cleaned a small amount of buildup on the sensors. We'll see if it works.

 

[whynotzoidberg]

I managed to reset the computer and clean all the sensors, and the code came back about a week later. I didn't have time to check it out, and I drove it about 100 miles and it cleared itself. No issues since.